IGN has an interesting article up on the beginnings of DayZ.
Dean Hall told the site that he got the idea after serving in the New Zealand Armed Forces. He was dropped into a Brunei jungle for a 30-day survival exercise, which he said gave him the spark.
“I became very interested in a survival-type game, in the levels of subtleties and decision-making that’s forced on you based on an emotional context. What happened in Brunei made me really reflect on those elements of the training exercise that brought out an emotional response in me. That’s what DayZ is all about,” Hall said.
The interview also talks about the decision to start characters unarmed, and the possibility of a standalone version that doesn’t need ArmA II on PC.
Make sure to check out the story, it’s definitely worth a read.